Two-stage catalytic hydrogenation process for upgrading crude shale oil



United States Patent 3,481,867 TWO-STAGE CATALYTIC HYDROGENATION PROCESS FOR UPGRADING CRUDE SHALE OIL Richard H. Dellert, Riverdale, Ill., assignor to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed Aug. 29, 1966, Ser. No. 575,516 Int. Cl. Cg 23/02 US. Cl. 208254 3 Claims ABSTRACT OF THE DISCLOSURE The pour point and the amount of nitrogen in crude shale oil are reduced by contacting the oil in a first stage with hydrogen and a catalyst comprising an iron group metal and a Group VIb metal oxide on an inert inorganic refractory oxide support at hydrogenation conditions of about 825 to 900 F. under a pressure of about 500 to 1,200 p.s.i.g., and contacting the liquid efiiuent from the first stage in a second stage with hydrogen and a catalyst of the class used in the first stage at milder hydrogenation conditions of lower temperature, and higher pressure.

This invention relates to an improved process for the treatment of crude shale oils. More particularly, it concerns a two stage catalytic hydrogenation process to upgrade crude shale oil.

Crude shale oil is obtained by retorting oil shale in a conventional, above-ground retort, such as the Bureau of Mines gas combustion retort. It is a highly unsaturated oil, and contains hydrocarbons and organic material composed of hydrocarbons in combinations with sulphur, nitrogen and oxygen. Crude shale oil is a distillate or overhead product which boils primarily in the range of about 400 to 1000 F. and thus contains essentially no distillate in the gasoline boiling range. Typical of its characteristics are: about 17 to 22 API gravity, about 300 SUS viscosity at 100 F., a pour point of at least about 75 F., about 0.21.5 weight percent sulphur, about 13 weight precent nitrogen, and a carbon to hydrogen weight ratio of about 7 to 7.5. Conventional refinery catalytic reforming and cracking processes cannot be used to treat crude shale oil because of excessive carbon or coke formation, which is ordinarily attributed to the high nitrogen and sulphur present in the oil feed. Also, because crude shale oil possesses a high pour point compared to conventional petroleum crude oils, it is too viscous for normal pipeline handling. Additionally, because it contains only a relatively small quantity (typically about 25%) of material boiling below about 650 F., it is not compatible with the capacities of downstream processing units in most refineries. Accordingly, in order to prepare a stock suitable for cracking or further refining, there is needed an improved process for upgrading crude shale oil.

By the process of the present invention an oil is produced which possesses a reduced pour point and viscosity, thereby improving its mobility for normal pipeline handling, and in addition the oil is of reduced nitrogen content tolerable in normal refinery catalytic units. Advantageously the yield and quality of material boiling below about 650 F. can be increased, and the quality of the material boiling above 650 F. is improved so that the total 650 F. and heavier fraction can be processed in a catalytic cracking unit.

According to the present invention, a two-stage catalytic hydrogenation process for upgrading crude shale oil is devised wherein crude shale oil is first catalytically treated in the presence of molecular hydrogen to produce a normally liquid shale oil intermediate product of re- 3,481,867 Patented Dec. 2, 1969 duced pour point. Any gas product from the first stage can be compressed and the liquid pumped to a second stage. The intermediate product is further subjected to additional hydrogen in the second hydrogenation stage in the presence of a catalyst and under conditions less severe than the first stage to substantially reduce the nitrogen content. The C and heavier intermediate shale oil product may have a pour point at least 30 F. below the feed stock, and the final product can be free of nitrogen, that is below about 0.1% N. It has been dis covered that while a combination of high temperature, low pressure and low space velocity favors pour point reduction, a combination of high temperature, high pressure, and low weight hourly space velocity is most desirable in maximizing denitrogenation. Accordingly, operating conditions are set in the first hydrogenation stage primarily to reduce the pour point, and in the second stage to minimize hydrocracking and maximize nitrogen removal. Both conversion stages are also attendant with sulphur and carbon residue reduction.

The catalyst found most suitable for use in either stage of the two stage catalytic hydrogenation process of the present invention can be any conventional hydrogenation catalyst known in the art such as any of the oxides and/ or sulfides of the transition metals, and especially an oxide or sulfide of an iron group metal, especially cobalt or nickel in amounts of about 215% by weight mixed with an oxide or sulfide of a Group VIb, metal, preferably molybdenum or tungsten in amounts of about 5l5% by weight. A suitable catalyst is a ,4 in. extrudate of 3% cobalt oxide and 10% molybdenum oxide on an activated alumina carrier. The catalytically active metals may be employed in undiluted form, but preferably they are supported on an absorbent carrier in proportions ranging from about 2 to 35% by weight. Suitable carriers include in general the inorganic refractory oxides, e.g., alumina, silica, zirconia, titania, and clays, etc. The preferred carrier is activated alumina.

The first stage treatment of the present process which is primarily concerned with pour point reduction is conducted at a temperature of about 825 to 900 F., a pressure of about 500 to 1,200 p.s.i.g., a weight hourly space velocity of about 0.3 to 4, and a hydrogen flow rate of about 2,000 to 10,000 s.c.f. of hydrogen charged per barrel of liquid feed. The second stage of the process which is designed to give maximum denitrogenation involves the use of higher pressures and lower temperatures than in the first stage, thereby minimizing hydrocracking and maximizing hydrogenation. The operating conditions of the second stage include a temperature of about 650 to 750 F., a pressure of about 1,500 to 3,000 p.s.i.g., but preferably at least 200 p.s.i.g. above the pressure in the first stage, a weight hourly space velocity of about 0.3 to 3, and a hydrogen flow rate of about 2,000 to 10,000 s.c.f. of hydrogen charged per barrel of liquid feed.

The following data show the effect of operating conditions on pour point, nitrogen content and carbon residue in the catalytic hydrogenation of crude shale oil according to the present invention.

Tests 1 and 2 indicate the eifect of temperature and show that by increasing the temperature from 800 to 850 F., the nitrogen content and carbon residue are reduced while pour point is relatively unaffected. Tests 2 and 3 indicate the eifect of pressure and show that, while high pressure contributes to a low nitrogen content and carbon residue, pour point is unchanged. Tests 3. and 4 show the effect of space velocity in that a lower space velocity contributes to a somewhat lower pour point. The data of Run 5 conducted according to this invention show that pour .point reduction takes place only at a temperature above about 800 F. and when low pressure is also employed.

The following example is illustrative of the present invention.

EXAMPLE I Crude shale oil having a pour point of 75 F. and a nitrogen content of 2.06 weight percent hydrogenated in a first stage over a cobalt-oxide molybdenum-oxide catalyst (containing approximately 2.5% by weight C and 8.5% by weight C 0 on an activated alumina carrier at a pressure of 1,000 p.s.i.g., a temperature of 850 F., a space velocity of 0.5 WHSV, and a hydrogen rate of 5,000 s.c.f./bbl. The C and heavier intermediate product thus formed has a pour point of 35 F. and a nitrogen content of 0.37 weight percent. The intermediate product is then hydrogenated in a second stage utilizing a nickel-oxide molybdenum-oxide catalyst (containing approximately 2.5% by weight Ni and 8.5% by Weight C 0 on an activated alumina base. The second stage is conducted at a pressure of about 2,000 p.s.i.g., a temperature of 725 F., a space velocity of 0.5 WHSV, and a hydrogen flow rate of 5,000 s.c.f./bbl. The resulting synthetic crude oil contains 0.07 weight percent nitrogen.

I claim:

1. A process for upgrading crude shale oil boiling in the range of about 400 to 1000 F. having an API gravity of about 17 to 22, and a nitrogen content of about 1 to 3 weight percent, which consists essentially of contacting said oil with hydrogen gas and a hydrogenation catalyst 40 consisting essentially of an iron group metal and a Group VIb metal on an activated alumina support, in a first stage hydrogenation zone at a pressure of about 500 to 4 1,200 p.s.i.g., a temperature of about 825 to 900 F., a space velocity of about 0.3 to 4 WHSV, and about 2,000 to 10,000 s.c.f of hydrogen per barrel of shale oil, to form a normal liquid intermediate product possessing a reduced pour point of at least about 30 F. below the feed stock, and contacting said intermediate product with hydrogen gas and a catalyst selected from the class used in the first stage to efiect denitrogenation in a second stage hydrogenation zone at a pressure of about 1,500 to 3,000 p.s.i.g., a temperature of about 650 to 750 F., a space velocity of about 0.3 to 3 WHSV, and about 2,000 to 10,000 s.c.f. of hydrogen per barrel of liquid 'feed to form an oil having a nitrogen content reduced below about 0.1 percent by weight of the oil product.

2. A process for upgrading crude shale oil as set forth in claim 1 wherein the iron group metal is selected from the group consisting of the oxides and sulfides of cobalt and nickel and the Group VIb metal is selected from the group consisting of the oxides and sulfides of molybdenum and tungsten.

3. A process for upgrading crude shale oil as set forth in claim 1 where in the first stage the hydrogenation catalyst is a cobalt-oxide molybdenum-oxide catalyst on an activated alumina carrier, the pressure is about 1,000 p.s.i.g., and the temperature is about 850 F., and in the second stage, the hydrogenation catalyst is a nickel-oxide molybdenum-oxide catalyst on an activated alumina base, the pressure is about 2,000 p.s.i.g. and the temperature is about 725 F.

References Cited UNITED STATES PATENTS 3,017,345 1/1962 Eastman et al. 208-210 3,025,231 3/1962 Friedman et a1 208-210 3,180,820 4/1965 Gleim et al. 208-210 3,277,199 10/1966 Poll.

3,297,563. 1/1967 Doumani 208210 3,362,901 1/1968 Szepe et al. 208210 DELBERT E. GANTZ, Primary Examiner G. J. CRASANAKIS, Assistant Examiner 

